Secure Digital - Wikipedia. Secure Digital (SD) is a non- volatilememory card format developed by the SD Card Association (SDA) for use in portable devices. The standard was introduced in August 1. San. Disk, Panasonic (Matsushita Electric) and Toshiba as an improvement over Multi. Media. Cards (MMC). The three companies formed SD- 3. C, LLC, a company that licenses and enforces intellectual property rights associated with SD memory cards and SD host and ancillary products. The SDA uses several trademarkedlogos owned and licensed by SD- 3. C to enforce compliance with its specifications and assure users of compatibility. ![]() Product Description. High speed USB2.0 transmission port, transfer rate up to 480Mbps. Backward compatible with USB1.1 standard. Plug & Play and hot swappable. Download iCare Data Recovery Pro Free Edition to rescue files from damaged. Memory card recovery software to fix memory card not formatted error. Memory card has been used a lot on digital cameras, mobile phones, external usb device, voice. The four families are the original Standard- Capacity (SDSC), the High- Capacity (SDHC), the e. Xtended- Capacity (SDXC), and the SDIO, which combines input/output functions with data storage. Electrically passive adapters allow a smaller card to fit and function in a device built for a larger card. Many users have been complaining that their SD Cards are not being recognized in Windows 10, Windows 8 or in Windows 8.1. We go through their woes and also bring a. Download the latest Micro SD Card Reader device drivers (Official and Certified). Micro SD Card Reader drivers updated daily. Download Now. The SD card's small footprint is an ideal storage medium for smaller, thinner and more portable electronic devices. SD (SDSC). Secure Digital changed the MMC design in several ways: Asymmetrical shape of the sides of the SD card prevent inserting it upside down (while an MMC goes in most of the way but makes no contact if inverted). Most SD cards are 2. MMCs. The SD specification defines a card called Thin SD with a thickness of 1. SDA went on to define even smaller form factors. The card's electrical contacts are recessed beneath the surface of the card, protecting them from contact with a user's fingers. The SD specification envisioned capacities and transfer rates exceeding those of MMC, and both of these functionalities have grown over time. For a comparison table, see below. While MMC uses a single pin for data transfers, the SD card added a four- wire bus mode for higher data rates. The SD card added Content Protection for Recordable Media (CPRM) security circuitry for digital rights management (DRM) content- protection. Digital camera reviews - amateur to professional cameras, the latest industry news, public discussion forums, photo-quality printers and digital video. The Secure Digital High Capacity (SDHC) format, announced in January 2006 and defined in version 2.0 of the SD specification, supports cards with capacities up to 32. Shop from the world's largest selection and best deals for Computer Memory Card Readers & Adapters. Shop with confidence on eBay! Addition of a write- protect notch. Full- size SD cards do not fit into the slimmer MMC slots, and other issues also affect the ability to use one format in a host device designed for the other. The Secure Digital High Capacity (SDHC) format, announced in January 2. SD specification, supports cards with capacities up to 3. GB. The major compatibility issues between SDHC and SDSC cards are the redefinition of the Card- Specific Data (CSD) register in version 2. SDHC cards are shipped preformatted with the FAT3. Version 2. 0 also introduces a High- speed bus mode for both SDSC and SDHC cards, which doubles the original Standard Speed clock to produce 2. MB/s. SDXC adopts Microsoft's ex. FAT file system as a mandatory feature. Therefore, ex. FAT- formatted SDXC cards are not a universally readable exchange medium. Windows Vista (SP1) and later. ![]() Consequently, they may not accept SDXC cards reformatted as FAT3. FAT3. 2 on smaller cards (for SDHC compatibility). Therefore, even if a file system is supported in general, it is not always possible to use alternative file systems on SDXC cards at all depending on how strictly the SDXC card specification has been implemented in the host device. This bears a risk of accidental loss of data, as a host device may treat a card with an unrecognized file system as blank or damaged and reformat the card. The SD Association provides a formatting utility for Windows and Mac OS X that checks and formats SD, SDHC, and SDXC cards. UHS- I cards declared as UHS1. SDR1. 04) also support a clock frequency of 2. MHz, which could transfer 1. MB/s. Double data rate operation at 5. MHz (DDR5. 0) is also specified in Version 3. SDHC and micro. SDXC cards labeled as UHS- I. In this mode, four bits are transferred when the clock signal rises and another four bits when it falls, transferring an entire byte on each full clock cycle, hence a 5. MB/s operation could be transferred using a 5. MHz clock. UHS- IISpecified in version 4. MB/s (full duplex) or 3. MB/s (half duplex) using an additional row of pins. FD3. 12 provides 3. MB/s while FD6. 24 doubles that. Both are full- duplex. The physical interface and pin- layout are the same as with UHS- II, retaining backward compatibility. Use of UHS- I requires that the host device command the card to drop from 3. I/O interface pins and select the four- bit transfer mode, while UHS- II requires 0. The higher speed rates are achieved by using a two- lane low voltage (0. V pp) differential interface. Each lane is capable of transferring up to 1. MB/s. In full duplex mode, one lane is used for Transmit while the other is used for Receive. In half duplex mode both lanes are used for the same direction of data transfer allowing a double data rate at the same clock speed. In addition to enabling higher data rates, the UHS- II interface allows for lower interface power consumption, lower I/O voltage rates and lower electromagnetic interference (EMI). SD card speed is customarily rated by its sequential read or write speed. The sequential performance aspect is the most relevant for storing and retrieving large files (relative to block sizes internal to the flash memory), such as images and multimedia. Small data (such as file names, sizes and timestamps) falls under the much lower speed limit of random access, which can be the limiting factor in some use cases. This was superseded by the Speed Class Rating, which guarantees a minimum rate at which data can be written to the card. Whatever the bus rate, the card can signal to the host that it is . Compliance with a higher speed rating is a guarantee that the card limits its use of the . Both read and write speeds must exceed the specified value. The specification defines these classes in terms of performance curves that translate into the following minimum read- write performance levels on an empty card and suitability for different applications. Class 1. 0 asserts that the card supports 1. MB/s as a minimum non- fragmented sequential write speed and uses a High Speed bus mode. The graphical symbol for the speed class has a number encircled with 'C' (C2, C4, C6, and C1. UHS- I and UHS- II cards can use UHS Speed Class rating with two possible grades: class 1 for minimum read/write performance of at least 1. MB/s ('U1' symbol featuring number 1 inside 'U') and class 3 for minimum write performance of 3. MB/s ('U3' symbol featuring 3 inside 'U'), targeted at recording 4. K video. Manufacturers can also display standard speed class symbols (C2, C4, C6, and C1. UHS speed class. Video Speed Class defines a set of requirements for UHS cards to match the modern MLC NAND flash memory. The combination lets the user record HD resolution videos with tapeless camcorders while performing other functions. It is also suitable for real- time broadcasts and capturing large HD videos. The most important advice. Applications that require a specific speed class usually specify this in their user manuals. Basic cards transfer data at up to six times (6. The 2. 0 specification. Manufacturers may report best- case speeds and may report the card's fastest read speed, which is typically faster than the write speed. Some vendors, including Transcend and Kingston report their cards' write speed. For example, a high- definition camcorder may require a card of not less than Class 6, suffering dropouts or corrupted video if a slower card is used. Digital cameras with slow cards may take a noticeable time after taking a photograph before being ready for the next, while the camera writes the first picture. The speed class rating does not totally characterize card performance. Different cards of the same class may vary considerably while meeting class specifications. A card's speed depends on many factors, including: The frequency of soft errors that the card's controller must re- try. Write amplification: The flash controller may need to overwrite more data than requested. This has to do with performing read- modify- write operations on write blocks, freeing up (the much larger) erase blocks, while moving data around to achieve wear leveling. File fragmentation: where there is not sufficient space for a file to be recorded in a contiguous region, it is split into non- contiguous fragments. This does not cause rotational or head- movement delays as with electromechanical hard drives, but may decrease speed; for instance, by requiring additional reads and computation to determine where on the card the file's next fragment is stored. In addition, speed may vary markedly between writing a large amount of data to a single file (sequential access, as when a digital camera records large photographs or videos) and writing a large number of small files (a random- access use common in smartphones). A study in 2. 01. Class 2 cards achieved a write speed of 1. MB/s, while all cards tested of Class 6 or greater (and some of lower Classes; lower Class does not necessarily mean better small- file performance), including those from major manufacturers, were over 1. There are both reversible and irreversible host commands that achieve this. Write- protect notch. The mini. SD and micro. SD formats do not support a write protection notch. When looking at the SD card from the top, the right side (the side with the beveled corner) must be notched. On the left side, there may be a write- protection notch. If the notch is omitted, the card can be read and written. If the card is notched, it is read- only. If the card has a notch and a sliding tab which covers the notch, the user can slide the tab upward (toward the contacts) to declare the card read/write, or downward to declare it read- only. The diagram to the right shows an orange sliding write- protect tab in both the unlocked and locked positions. The presence of a notch, and the presence and position of a tab, have no effect on the SD card's operation. A host device that supports write protection should refuse to write to an SD card that is designated read- only in this way. Some host devices do not support write protection, which is an optional feature of the SD specification. SD Card Reader says the card is write- protected. Indeed. I used to think that the write- protect tab operated a switch inside the card. Not true - the tab is a purely mechanical flipper, with no electric connection inside the card. Instead, it toggles (or fails to toggle) an electro- mechanical switch in the SD card reader. Oh my, even the venerable floppy drives used to have an optical sensor for the write- protect tab, and I don't remember ever meeting a flawed write- protect sensor in a floppy drive.. Whereas with the ultra- modern SD media, it seems to be a popular flaw : -/Taping over the write- protect tab on the SD card may indeed help, if the mechanical switch inside the reader is flawed in exactly the right way. In my case, it was flawed worse. On my Fujitsu Siemens notebook, otherwise an excellent reliable machine, I managed to find out that the metallic finger in the slot is free- floating when the slot is empty, but gets grounded if the finger is pressed. Next, I was lucky several times. Without voiding any warranty sticker, I managed to find the right hood on the bottom of the notebook, which revealed access to the CPU, RAM and basically the whole motherboard, including the SMT pins of the SD reader socket. I quickly found the sensor pin, it was the left- most pin on the socket. And indeed, if I inserted an actual card, the sensor kept trying to close, but remained open most of the time. Then I finally I got the idea that I could just short the pin to ground . Put a very sharp tip on my soldering iron, got about 1 cm of hairline wire (a single strand from a piece of left- over stranded wire), and did the micro- surgery. I merely needed to cross a narrow gap between the sensor trace and a nearby ground plane, and I zapped my piece of wire to the right pins of two suitable SMT devices, which provided uncovered tin, easy to solder. Guess what, the SD card isn't write protected anymore, even if I toggle the tab on the card to the . Who cares about the write- protection anyway : -)Thanks a lot, everyone, for posting your comments about the tape- over trick, and especially about the . That got me started. Your information has saved me from several days without my notebook, and possibly from a replacement of my known- good rock- solid motherboard (if it ain't broke, don't fix it).
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